What makes sea-level rise?

Last week the science community was shocked by the claim that 42% of the sea-level rise of the past decades is due to groundwater pumping for irrigation purposes. What could this mean for the future – and is it true?

The causes of global sea level rise can be roughly split into three categories: (1) thermal expansion of sea water as it warms up, (2) melting of land ice and (3) changes in the amount of water stored on land. There are independent estimates for these contributions, and obviously an important question is whether their sum is consistent with the total sea level rise actually observed.

foto (c) Stefan Rahmstorf 2012
In the last IPCC report (2007), the time period 1961-2003 was analysed in some detail, and a problem was found: the individual contributions summed up to less than the observed rise – albeit with rather large uncertainties in the estimates. In the years since then, much research effort has been devoted to better quantify all contributions. For the last decade there is also improved observation systems, e.g. the GRACE satellite mission and thousands of autonomous ARGO floats monitoring globally the warming ocean.

Last year Church et al. (2011) provided a new sea-level budget analysis (see Fig. 1). For the period 1972-2008 the budget is closed, with a total rise of about 7 cm. A bit over half of that is due to melting land ice, and a bit less than half due to thermal expansion. Land water storage makes a small negative contribution, because the water stored in artificial reservoirs (which lowers sea level) is estimated to be larger than the amount of fossil groundwater pumped up for irrigation (which mostly ends up in the sea). Also for the shorter recent period 1993-2008 (for which we have satellite measurements of global sea level rise, found to be about 3 mm per year) John Church and colleagues successfully closed the sea level budget. Granted, the uncertainties in the estimates are still significant so the issue cannot be considered completely resolved. Nevertheless, the Church et al. paper defines the current state of the art against which all further studies need to measure up.

Fig. 1. Sea level rise for 1961-2008. On the left the individual contributions are shown, on the right the sum of these contributions (red) is compared to the measured rise (black). Graph from Church et al. (2011)

The groundwater shock

On May 20, Nature Geoscience published a Japanese model simulation of global land water storage (Pokhrel et al. 2012), which surprised the expert community with the conclusion that 42% of sea level rise (about 3 out of 8 cm) over the period 1961-2003 is due to reduced land water storage. In contrast to earlier studies, reservoir storage was assumed to be smaller, but mainly groundwater pumping was calculated to be several times larger.

Are the new numbers realistic? I and many colleagues I spoke to have serious doubts. It is a model result which is in stark contradiction to data-based estimates. The simulation is based on a simple assumption: first the total water demand was estimated, second the availability of near-surface water, and then the shortfall was assumed to be completely supplied by unlimited use of fossil water. The realism of this assumption is debatable – to me it seems to run a risk of greatly overestimating the withdrawal of fossil water.

The uncertainties also need to be discussed: the fossil water withdrawal is estimated by subtracting two large, uncertain numbers. Yet there is no proper uncertainty analysis. Instead, a single number with three significant digits is presented (359 km3 per year for 1950-2000). That is almost five times the rate of 82 ± 22 km3 per year computed by Konikow (2011) for 1961-2008, based on data for groundwater usage and actual observations of water-level declines in aquifers being depleted. Leonard Konikow, a hydrologist with the US Geological Survey, says about the huge amount of groundwater depletion simulated by Pokhrel: “Groundwater hydrologists would have noticed if such a large volume of water were ‘missing'”.

A bit dubious is also the fact that for the largely overlapping period 1950-2000 Pokhrel et al. find that less than 20% of sea level rise is due to land water storage, not 42% as for 1961-2003. Yadu Pokhrel responded to my query that this is due to a large short-term increase in the landwater contribution to sea level between 2000 and 2003, combined with the fact that their rates are computed simply from the difference between the end points (2003 minus 1961). 2003 happened to be a drought year with little water stored on land. Church et al. compute their budgets based on linear trends, which is more robust by using all data points and not just the end points.

Pokhrel et al. don’t even mention the Church et al. paper (although that was published before their paper was submitted). They relate their discussion to the old IPCC finding of “missing sea level rise”, claiming to now have found the source of this missing water. The media largely followed this story line.

Impact on future projections

If the Pokhrel numbers were right, what would this mean for the future? There are two methods to estimate future sea level rise: complex process-based models, which try to compute all individual contributions (e.g. glacier melt) under changing climate conditions, and semi-empirical models, which exploit the observed relationship between global temperature and sea level and are calibrated with past data (see my article Modeling sea level rise at Nature Education). Both have their problems and limitations, and currently I don’t think anyone can seriously claim to know which will turn out to be closer to the truth.

Fig. 2. Change in sea level in mm per year due to the contribution of groundwater pumping (black curves – estimated based on data by Konikow 2011 and Wada et al. 2010) and water storage in artificial reservoirs (blue – this contribution is negative, i.e. lowers sea level). From Rahmstorf et al. (2011).

For the process-based models, the high fossil water pumping rates according to Pokhrel would simply have to be added to the projections (artificial reservoirs are generally thought to not offset much of this in future, because reservoir construction is well past its peak and there is not much scope for a large expansion). Last year we published simple projections of the groundwater pumping contribution (Rahmstorf et al. 2011, see Fig. 2), based on the data by Konikow (2011) and an earlier study by Wada et al. (2010) together with the medium UN global population projection. In the upper of the two curves, groundwater pumping raises sea level by 10 cm by 2100. If, based on Pokhrel, we assume groundwater pumping rates that are roughly twice as high, this could add 20 cm to sea level. Very recently, a new study by Wada et al. (2012) gave a more detailed projection up to 2050 which lies in between our two curves. By 2050 they find 2-4 cm sea level rise due to groundwater pumping. If the rate did not increase any further after 2050, this would add up to 5-8 cm by 2100. Whether 5, 10 or 20 cm – it is clear that groundwater pumping is a factor that must be accounted for in future sea level projections.

The impact of groundwater pumping on semi-empirical projections is smaller, because here we have two partly compensating effects. On one hand there is the added water as just discussed, on the other hand the climate-related part of the projection gets smaller, since the climatic effect on past sea level rise is also smaller, which affects the calibration of the model. In our paper we found that accounting for groundwater depletion according to Wada (i.e. upper curve of Fig. 2) lowers the projections for a moderate global warming scenario (RCP4.5) by 6 cm. If we assume again that Pokhrel’s numbers are roughly twice as high as this, also for the future, then our best estimate for this scenario would come down to 91 cm sea level rise, as compared to 98 cm in our ‘default case’ (for which we used the lower curve of Fig. 2, based on the Konikow data).

Overall, accounting for the Pokhrel landwater estimates would thus tend to increase the process-based sea level projections and lower the semi-empirical projections, thereby reducing the discrepancy between the two – in my view a very welcome feature. But do I believe it?

168 Responses to “What makes sea-level rise?”

Even if OTEC could produce electricity be harvesting heat from warm(ed) surface waters at, say 5-10% efficiency, why would you go through the trouble and expense of “hiding” the heat rejected (>90%)in deep ocean layer, when it could be rejected instead, (much more easily) directly to the upper troposphere (above CO2 layers)-a location where heat could more efficiently be radiated to outer space.

Nature accomplishes this easily from locally warm water via waterspouts, videos of which one can easily find on the internet.

Further, the amount of heat transported upward by a single hurricane would far exceed anything that could be accomplished by going through the expense (including pumping and heat-transfer equipment) of building OTEC machines.

One technology for “greening the desert” that has already been proven is Charlie Paton’s Seawater Greenhouse. I might add that one doesn’t necessarily have to “desalinate” seawater to effectively use it’s “humidification potential”. The chemical potential of (pure) water (vapor pressure) over seawater is about 98-99% of fresh water. One just has to figure out ways of controlling (containing) evaporation and rejecting the (enriched) brine back into the sea after some of the fresh water has been removed from it.

Ron Manley:
Doesn’t the water that evapotranspirates in the desert fall as rain somewhere else and end up in the ocean? The amount of water vapor in the air is roughly the same all the time (increasing slowly due to increasing temperature). Fossil water brought to the surface ends up in the ocean, even if it does not enter a river to flow there.

Jim Baird’s proposal to irrigate the desert to get rid of water does not appear to account for the evaporation loss either. If you put 2 meters of water on the land to irrigate it you do not sequester 2 meters of water forever. Most of the water evaporates and is not sequestered.

I am beginning to get the same feeling I get when I listen to the guy who thinks that all our energy and CO2 problems can be solved with a Tesla turbine/pump.

As for OTEC, it is theoretically only 5% to 7% efficient and I believe that demonstrations have been much less. So, the process harnesses energy flow between warm surface and deep cool water, thus effectively mixing them, while converting a small percent of the flow into electricity. When the electricity is used it is ultimately converted back to heat and this is a net wash. By itself, deriving all of our energy needs from OTEC would have very little effect on the thermal expansion of the oceans, only stopping CO2 pollution will. CO2 is the gift of chaos that keeps on giving.

What I would like to know is what is the cost per watt for OTEC relative to, for example, PV (photovoltaics- please explain acronyms). Steve

A true desert is described as a landscape receiving less than 250 millimetres (10 in) of average annual precipitation, which is not enough to sustain plant life.

The U.S. Geological Survey says the rate of application of water for irrigation purposes is 2.48 acre-feet. There is clearly therefore a lot of room for sequestering water in the desert that otherwise would be adding to sea level rise.

David Miller, a statistical analysis of 55 years of cloud cover and temperature observations for the north-eastern Pacific Ocean by Amy Clement and Robert Burgman of the University of Miami and Joel Norris of the University of California-San Diego found that low-level cloud cover decreases as temperature increases — and that a feedback mechanism arose. As the water warms the atmosphere warms – the water warms more.

I guess the question is, is the greater danger in action or inaction?

Personally, on behalf of my grand kids, I would prefer to try to solve the problem.

In response to some other posts it is the surface temperature that is producing this effect and also the thermal stratification that is threatening phytoplankton, the source of half the oxygen we breath and the base of the ocean food chain.

Tohihiko Sakurai makes the case in US application Publication No. US 201000018567, Solar Power Generating System Employing a Solar Battery and Publication 20100300095, the problem is significant enough he would use OTEC simply to pump deep water to the the surface for no other reason than to cool it.

And of course it is surface temperature which drives hurricanes so mixing that heat to the depths can’t be all bad.

Jim,
You apply 2.5 acre feet of water to irrigate the plants. Most of the water evaporates and returns to the ocean. It is not sequestered in the soil. Farmers only add as much water as they need to to grow the plants, not enough to saturate the soil kilometers deep. Why should anyone listen to you when your basic facts are so completely wrong? Your claims about ocean energy also do not withstand minimal scrutiny.

Though correlation is not necessarily causation, (pardon the pun), I would argue that sea level rise probably tends to have more of a ’cause’ than a ‘maker’…

BTW, for the record, “What makes sea level rise” is perfectly acceptable usage! In the sense of what makes it work. This is probably closer to a mechanistic and scientific explanation. Cause or reason can also imply more of a legalistic argument that might be better suited for a debate among lawyers. Ain’t language and etymology fun?

This from a Brazilian born, native speaker of American English, (yes, that is possible) and of mixed Hungarian and Danish ancestry.

You might of course prefer to discuss the nuances of Latin influence on the Anglo Saxon vernacular with a Frenchman… but do stay away from the Finno-Ugric perspective >;^)

I believe I put a number on the heat to depth in 48. The thermodynamic efficiency with conventional OTEC is just less than 5% in best cases. You dump therefore about 21 watts of surface heat to the depths for every 1 watt of power you produce. The thermal expansion you would reduce would be the amount that would arise from the 1 watt of heat that was instead turned to 1 watt of electricity.

I also tried to explain that because of this massive dumping from the surface to the depths you degrade the capacity of the ocean to produce OTEC power and accordingly the amount of heat you can covert to power and by extension the thermal expansion you reduce.

Gerard Nihous wrote a paper a few years back that estimated the max you could get out the ocean would be 5TW a year. Martin Hoffert said he was a fan of OTEC but it couldn’t produce as much energy as he was looking for which was 30TW.

To try and overcome this limit I propose a counter-current heat flow mechanism that would bring most of the 20 watts back to the surface again like hurricanes do. I would like to see Smalley’s 60 TW or Hoffert’s 30 TW, which ever you prefer, produce by converting 60TWh or 30 TWh of ocean energy and the amount of thermal expansion deep or shallow would be that 30 or 60 TW worth.

Martin says the the 2.5 TWe would be consumed and become heat again. Of course it would put that would apply to the 2.5 TWe you produced with nuclear power also plus except in that case you produced 5TWh in entropy as well. In other words 2.5TWe of OTEC is 3 times better in terms of thermal expansion of the ocean as 2.5 TWe of nuclear power.

Susan, I welcome the skepticism and do learn from it.

I have also seen it lead to paralysis. Over 20 years ago I invented the Subductive Waste Disposal Method for the elimination of nuclear waste. There were all kinds of skeptics then as well. e.g. local scientists believed they found water movement near where the repository would be located. Funny thing is a couple of years ago the Russian developed a whole new idea of depositing nuclear waste in deep boreholes with active hydrology because that is how most of the most valuable ore bodies are formed.

Funny thing is the same Natural phenomena that would have eliminated both spent fuel and excess weapons material instead precipitated the Fukushima disaster and the same province of Canada that could have provided the solution was instead the first down winder to receive the fallout. With potentially a lot more to come if Reactor 4 keels over.

In other words 2.5TWe of OTEC is 3 times better in terms of thermal expansion of the ocean as 2.5 TWe of nuclear power.

This is interesting only if you ignore the elephant in the room: the heating caused by released greenhouse gases. In this respect, both are completely negligible (if done right) compared to fossil fuels.

BTW another detail that’s easily overlooked: the thermal expansion coefficient of water is a very nonlinear function of temperature. This makes moving 50 TW of heat down from the warm surface layers to cold depth a seriously non-neutral proposition, expansion wise!

#51 – Michael Sweet
“Doesn’t the water that evapotranspirates in the desert fall as rain somewhere else and end up in the ocean?” Not necessarily. After all, if all the extra evaporation, whether from irrigation or CO2 induced global warming, ended up as rain in the oceans, not as increased water vapour or clouds, there would be no positive feedback and climate change would be manageable.

#53 Jim Baird
“Ron, I do account for evaporation.”
Jim, when I made my statement about little attention to evaporation from irrigation I was referring to the suggestion in the nature paper that 42% of the sea level increase was due to groundwater pumping. With regard to your proposal, fossil aquifers are typically 300 to 500m deep. Can I suggest you also calculate how much CO2 would be relased by the energy needed for pumping ?

Speaking of sea level rise, I live in North Carolina. When I recently told my girlfriend about our legislature’s response to sea level rise, her response was “what a complete waste of stupidity!” – an elegant counterpart to “not even wrong.”

dbostrom, US, New Zealand and Canadian patents say otherwise. It was the only solution that accessed a subduction zone from land and thus was never banned by the London Dumping Convention despite all claims to the contrary.

Ron Manley, all pumping I proposed is powered by renewable sources. Further hydrogen produced by OTEC power and electrolysis can rise by its own buoyancy to an elevation where it could produce both power and water that would flow to where it is required without the need of pumping.

Martin, I was not aware of the non linear expansion. Perhaps we could discuss privately so as not to offend owl905

“The reasonable agreement in recent years between the observed rate of sea level rise and the sum of thermal expansion and loss of land ice suggests an upper limit for the magnitude of change in land-based water storage, which is relatively poorly known.”

Deep ocean warming solves the sea level puzzle
“… Model result for sea level rise from thermal expansion of the deep ocean. Simple addition of the numbers above (1.2 + 0.85 mm/year = 2.05 mm/year) shows that the result from the upper ocean thermal expansion and addition of water mass is still about 1 mm/year short of the observed 3.1 mm/year …”

Aside — floating ice displaces almost exactly its own weight in sea water– not quite, because “the ice is fresh water and the sea is denser salt water. However, the effect is tiny. Melting 1 kg of floating ice increases the sea level as much as melting around 30g of ice on land”
csiro.au/helix/sciencemail/activities/icemelt.html

When water freshly melted from sea ice warms up, how much does its warming cause it to expand, and does that change its contribution to sea level?

(As Martin notes it’s nonlinear, and I don’t find the numbers handy for either the temperature change or the expansion — I’m wondering how much the temperature of the meltwater changes as it mixes into the local cold polar ocean, first, then into the average global water temperature over time).

I assume it’s a trivial amount, considering the rest of what’s happening.

Hank Roberts, thanks for the references. The skeptical science piece references the study of Purkey and Johnson, which is persuasive. It is logical deep water would be warming, apparently faster than predicated by the circulation models, thus it would contribute to sea level rise through expansion.

My proposal is to convert some of this heat to energy to alleviate the problem. Full stop.

OK, Jim Baird described his patented idea to dig a tunnel to what may or may not be a subduction zone “… off the west coast of Vancouver Island…. at a distance 50-70 kilometers from the western terminus of the line. Accessing the Explorer Crust at the depth show, from the Brooks Peninsula, could be accomplished with conventional tunneling techniques.”http://www.nwmo.ca/uploads_managed/MediaFiles/1287_baird-submissiononthetopic_cho.pdf

It’s a fascinating area geologically speaking, with many surprises, and much sea level research has also been going on throughout the Cascadia subduction zone. There are terraces from changes around the ice age and from large vertical movements during subduction quakes, so even establishing “sea level” for any given location over geological time isn’t all that assured.

“Japanese Ultra-deep Drilling and Geoscientific Experiments (JUDGE project) is a proposal …to conduct land-based drilling at southern Kanto region to intersect the subduction zone that exist at a depth of 10 km … to penetrate through the earthquake source fault of giant inter-plate earthquake which did and will continue to attack Kanto area…. to widen the option on geological disposal of high level radioactive waste for a country like Japan that locates in the subduction zone.”

There’s much that could be discussed (again, decades after the first go ’round) about disposal of effluvia in deep ocean trenches but perhaps the unforced variations thread would be a better place? Or somewhere else entirely? The connection w/climate is not clear other than as a indicator of lack of confinement by practical considerations.

A study published today in Nature Climate Change projects further disruption to supply (electricity), with a likely decrease in thermoelectric power generating capacity of between 6-19% in Europe and 4-16% in the United States for the period 2031-2060, due to lack of cooling-water. The likelihood of extreme (>90%) reductions in thermoelectric power generation will, on average, increase by a factor of three.

What then is the rationale thing to do? Contribute even more entropy to the system or convert the heat already doing damage to productive use?

Hank the Explorer Plate is a complicated region and there are arguments on both sides whether it is still subducting. The fact the triple point between the three plates is continuously moving northward suggests to me it is. If it is not on the other hand, placing waste in it beneath the sedimentary layer of about 2K gives you 2K more buffer than any other proposal to deposit nuclear waste in the seabed. A solution that is still considered technically sound. The push against it was lead by Maurice Strong, who at the time was a director of Molten Metal Technologies that was pushing a now debunked alternative. The political shenanigans in that episode make for interesting reading. Unless of course you were affected.

Per Martin Vermeer’s grammar nit: As a native US English speaker, I agree with him. To me, “sea level” is a phrase that is not normally hyphenated when used as a noun phrase, but becomes hyphenated when it is used as a modifier.

So it’s “What makes sea level rise?” but “What causes sea-level rise?” since in the latter case “sea level” has become a modifier for “rise”.

Hank re 75, me too last digression. The JUDGE project grew out of a proposal by Masao Kasuya, “Sub-Seabed Disposal Using a Submarine Tunnel – A solution to High-Level Radioactive Waste Disposal in Japan.” in which he stated, “I would like to thank Mr. J. R. Baird of British Columbia Canada for providing useful information and sharing out his insight.”

In personal correspondence he stated, “You have presented a brilliant idea of drilling a tunnel from land, instead of drilling holes from the sea floor. This method is definitely irrelevant to the London Dumping Convention because waste would never go through seawater during the disposal. . . It is regrettable anyway that the LDC is being politically used for impeding sincere efforts to find technically sound solutions.”

I brought it up because it is a cautionary tale of how legitimate solution are snuffed out with consequences.

3. DOE spent how many billions on Yucca Mountain after 1996 when water problems were discovered, which the science suggested and the law provided should have disqualified the site. DOE’s and Congresses’ response was to change the law instead. – Say Amen to the nuclear industry thanks to this kind of oversight.

4. Canadian taxpayers say Amen to their $20 billion investment in CANDU reactors thanks in no small part to the waste and proliferation issues this solution would have provide.

Sorry last comment on subduction of Explorer Plate. I put my cursor on the current site of the Explorer Plate in an old Microsoft Video on plate tectonics. In about 50 million years the cursor is sits in the Midwestern United States.

How this happens without the Explorer Plate being subducted is beyond me.

How much of sea level rise is due to soil and silt being deposited into the oceans from rivers?

How much of sea level rise is due to erosion of coasts by the action of wind and waves?

How much of the apparent sea level rise is due to subsidence of the continents?

How much of sea level rise is due dust being blown out deserts and falling into the oceans?

WRT to the latter. I have seen a documentary on the TV that so much dust was blown out of west Africa and deposited in various Caribbean islands the natives were able to use for making pottery and clay tiles.

Possible factors responsible for world-wide sea level changes are reviewed. The major causes are variations in the volume of land ice and changes in oceanic ridge systems, with sediment accumulation in the oceans and desiccation of isolated basins producing second-order effects. Alterations in effective water volume (by ice sheet growth or desiccation) are much faster than changes in ocean basin capacity, but the latter are considered likely to be the cause of long-term trends, which are ultimately related to the history of mantle convection.

Sedimentation apparently requires millions of years to effect significant changes.

Get the whole combination plate including a side of context w/this chapter

Yet another diversion:
#54
“A true desert is described as a landscape receiving less than 250 millimetres (10 in) of average annual precipitation, which is not enough to sustain plant life.”

Many people here in the Southwest would take issue with your statement that 250 mm/yr is not enough to sustain plant life. Our deserts have their own specially-adapted species of plant life that are just fine with a 250 mm/yr or less.

There seems to be two distinct camps regarding the input of groundwater depletion. The CSIRO, Chu, and Moore(Annals of Glaciology, 2011), view it as a minor effect; while the new paper is a high-end revision of Marc Bierkens’,Utrecht University, study in 2010 which pegged the contribution at.57mm annual in 2000:

Jim – If we assume that all of the water taken from particular fossil aquifers where sea level intrusion is taking place is returned to the sea, then the positive term might roughly cancel the negative term. But if a significant fraction of the “upstream” fresh fossil water is being used to support lush new moisture-laden vegetation, filling reservoirs, bottled for use elsewhere, and filling suburban swimming pools and toilet tanks…then not so much balance.
Harold – No, Chu 2001 does not mention seawater intrusion. That does not mean it is insignificant.

Fixation of carbon to calcium and magnesium carbonates by shell-forming creatures could contribute to sea-level rise. When these creatures die, their shells fall to the ocean floor which would increase sea level as these depsits build up. However this probably a slow process.

The more interesting question, it seems to me, is what prevents this rise?

To summarize, I propose:

1 Converting ocean heat to energy to prevent thermal expansion.

2 Capturing water that otherwise would enter the ocean or desalinating and moving ocean water to productive terrestrial use. (the deserts are the only location on the planet capable of accepting the volumes required and would benefit most from the enterprise.)
3 Converting ocean volume to its gaseous components and using the hydrogen in turn either as a transportation fuel (or as a component of another fuel) or as a water carrier.

These approaches would in turn draw down CO2 levels in both a cooler ocean and a fertile desert.

“Many people here in the Southwest would take issue with your statement that 250 mm/yr is not enough to sustain plant life. Our deserts have their own specially-adapted species of plant life that are just fine with a 250 mm/yr or less.”

Same thing here in South Australia. Generally speaking, saltbush country, though a lot of it supported extensive sandalwood scrubland before it was cleared for agriculture.

However, we do have Goyder’s line. http://en.wikipedia.org/wiki/Goyder's_Line. This turns out to be a pretty accurate 10 inch rainfall demarcation, though Goyder’s focus was more on unreliability of rainfall on the inland / desert side than on the amount.

I’m quite certain Jim intended to imply “convert energy of ocean heat to a form capable of doing work” but what jumped out at me is that we actually need is get the energy off the planet entirely (not within our means), hide it, or preferably reduce the amount being stored here (stunning insight, eh?).

Whatever energy is extracted from the ocean isn’t going to vanish from dynamics unless it’s applied to some sort of endothermic reaction building a stable compound. Failing locking it up, presumably energy extracted from the ocean will once again end up as heat in the atmosphere once it’s done doing work. Where does that leave us?

Jim’s thrust of course is that of geoengineering sea(-)level but– leaving aside practical considerations of harnessing OHC for work– if such a course were to be seriously investigated it seems worth doing rigorous evaluation as to whether work done to move water from A to B might better be applied elsewhere in a way that improves the energy budget of the planet.

Going from not knowing it happens to claiming it’s a benefit was rather quick.
You need to calculate the amounts involved here; I’d be surprised if you could claim any detectable benefit would happen after doing the math.

Seriously, if you put a discussion forum on your website you could be getting significant help (that is, serious criticism from knowledgeable people) that would, if incorporated in your plans, improve the credibility of the idea.

But with no numbers, you haven’t got an answer to contribute to the topic here.

Jim Baird @ 92 wrote: “3 Converting ocean volume to its gaseous components and using the hydrogen in turn either as a transportation fuel”

As soon as you burn that fuel the H will be incorporated right back into H2O, which will then precipitate back onto the surface, land, ocean, doesn’t matter. In other words, you’re only borrowing that H for a very short time. The net ocean volume flux would only equal the current global inventory of unburned H.

While Jim Baird’s suggested transportation of water inland to increase desert productivity hasn’t received much support here, I do believe it’s possible to “geoengineer” desert spaces “at the margins”, by “pushing the envelope” (dry line) farther inland, if you will.

Warm sea water would be transported a short distance inland through large pipes, or, in some cases, by building canals. There, Atmospheric Vortex Engines would be employed to evaporate the water, while at the same time, generating the necessary electrical energy required for its movement as well as to create sufficient “mass and heat transfer” surface to enable the evaporation. In “shoulder season” at least, this should fall nearby as rain.
The localized cooling would create a positive feedback, encouraging yet more rain to fall, if enough of the devices were built in a local area.

I think it’s also a concept worth consideration in the northeast Mediterranean, where there is a very warm bay from which water could be efficiently extracted. The objective would be to send enough water aloft which would fall as rain at the headwaters of the Euphrates River, to replenish this supply of freshwater, located in the mountains of Turkey. This would work best in the August-November period when the water is still warm (high vapor pressure) and the highland areas have cooled somewhat, promoting condensation.

In Australia, the person who knows most about the potential uses of the AVE there would be Don Cooper.

…the new paper is a high-end revision of Marc Bierkens’,Utrecht University, study in 2010 which pegged the contribution at.57mm annual in 2000:

The paper you link is actually the 2012 paper by the same team. Their 2010 paper found 0.8mm/yr contribution in 2000.

In the 2012 paper note that they indicate 2015 as the point at which total net terrestrial water storage will have a cumulative positive effect on sea level change. In other words, at this point in time they suggest human terrestrial storage activities have overall acted to lower sea level. This is very different to what Pokhrel et al. 2012 suggests.

dbostrom, my premise starts from Richard Smalley’s Terrawatt challenge. He estimated the world could need as much as 60 terrawatts and I am of a similar mind to his – the aspirations of the rest of the world for the living standard we on this continent take for granted are going to be hard to deny. (He has a wonderful lecture on YouTube http://www.youtube.com/watch?v=CpYTVMhPUzc in seven parts on the subject and spent his remaining days, while seriously ill, giving this lecture.)

By the way he ranked the most serious challenges we face as first energy and then water.

Starting from there I have tried to figure out how you could provide this kind of energy and water without ruining the planet.

My proposal stems from that premise and I believe would provide some environmental benefit in the production of OTEC energy that nevertheless will provide more heat in its use which might be inevitable in any case.

Hank Roberts, my email address is on the contact page of the website and I would welcome the serious critic of knowledgeable people to say nothing of their collaboration in an effort to solve the planets two greatest problems. Dr. Lau and I are trying to find the best way do reduce the parasitic losses inherent in using CO2 as a working fluid in OTEC and are seeking input on this problem and others. I hope that we could work together on these.

Not really sure how to up a forum on my page and my allotment of user space is pretty much maxed out.

Jim Eagers, that is why I propose Hydrogen as an energy carrier. It is light but hard to transport but in a desert environment would recombine to make the water I am looking for.

Jerry Toman, thanks for the contribution. The transportation problem is a huge one. That is why I think oil tankers deadheading to the MENA are a wasted opportunity that would be a good first step in this endeavor.

adelady, the definition isn’t mine it is Wikepedia’s, nevertheless in the states ,according to the U.S. Geological Survey, for the year 2000, the rate of application of water for irrigation purposes was 2.48 acre-feet (730 mm). At that rate the desert would take up just about all of the annual projected rise over the next century.

Have they taken in to account irrigation, which diverts much water which would have reached the sea over parched land instead? It’s not all the result of big dams, much of it being small scale. This must be a big offset.